Image recording apparatus, image recording method, and non-transitory computer-readable storage medium

ABSTRACT

According to an aspect of the present invention, temperatures at a plurality of different positions in an array direction in an ejection opening array are detected, and heating by a heating element is executed in a case where a temperature difference between the temperatures is higher than a predetermined threshold.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an image recording apparatus, an imagerecording method, and a non-transitory computer-readable storage medium.

2. Description of the Related Art

Up to now, an image recording apparatus in which ink is ejected while arecording head having an ejection opening array constructed by arranginga plurality of ejection openings for ejecting ink is scanned withrespect to a recording medium to record an image on the recording mediumhas been proposed.

In the above-described image recording apparatus, a recording systemwhere an electrothermal transducing element is used, and thermal energygenerated when a pulse is supplied to the electrothermal transducingelement is utilized to eject the ink from the ejection openings has beenproposed. According to the above-described recording system, even whenthe thermal energy is uniformly applied to the plurality of ejectionopenings in the ejection opening array, a temperature distribution ofthe ink in accordance with array positions of the ejection openings maybe generated in some cases. Since the ejection amount of ink isincreased as a temperature of the ink is higher, the ejection amountfluctuates among the ejection openings in accordance with thistemperature distribution, and as a result, density unevenness may occurin the image to be recorded.

To suppress the above-described density unevenness, Japanese PatentLaid-Open No. 4-250057 discloses that a recording head including aplurality of temperature sensors arranged at mutually differentpositions in an array direction of the ejection openings and atemperature adjustment heater that performs a temperature adjustment byheating an area in the vicinity of the ejection opening (hereinafter,will be also referred to as sub heater) is used. In more detail, arecording head including two sub heaters that can be mutuallyindependently driven which are arranged in the vicinity of one end partand the vicinity of the other end part is disclosed. Japanese PatentLaid-Open No. 4-250057 describes that, even in a case where atemperature difference of the ink between the vicinity of one end partand the vicinity of the other end part in the ejection opening arrayoccurs in a recording mode for performing the recording by decreasingthe number of ejection openings used for the recording, the temperaturedifference between the end parts can be eliminated by making powersettings in accordance with the temperature difference in the respectivesub heaters and independently driving the sub heaters while theabove-described recording head is used.

However, with the recording head of recent years, it is found that, evenin a recording mode in which all of the plurality of ejection openingsin the ejection opening array are used, for example, a temperaturedistribution in which a temperature on a central side in the ejectionopening array is higher than a temperature on an end part side may occurin some cases. In a case where the above-described temperaturedistribution occurs, density unevenness may occur in an area between anarea recorded from the central side in the ejection opening array and anarea recorded from the end part side in the ejection opening array onthe recording medium.

It is conceivable that this temperature distribution is derived, forexample, from a state where heat dissipation via a substrate more easilyoccurs in the end part in the ejection opening array and the temperatureis more easily decreased than the central part. In recent years, tosuppress a landing position deviation of the ink in the ejection fromthe end part in the ejection opening array, a technique has beenproposed with which the ejection amount from the end part side in theejection opening array is set to be lower than the ejection amount fromthe central side to perform the recording. In this case, the number oftimes to drive the electrothermal transducing element corresponding tothe ejection opening located on the central side in the ejection openingarray is increased, and the above-described temperature distribution maymore notably occur.

According to the technology described in Japanese Patent Laid-Open No.4-250057, since the sub heaters are provided only in both end parts inthe ejection opening array, the temperature distribution is noteliminated in the above-described case where the temperature at thecentral part in the ejection opening array is higher than thetemperature at both the end parts. In addition, since a configuration ofan electric circuit or the like becomes complicated in the recordinghead that can independently drive the plurality of sub heaters as inJapanese Patent Laid-Open No. 4-250057, an increase in a size of therecording head and an increase in costs may occur.

In addition, as described in Japanese Patent Laid-Open No. 4-250057, itis found that, even in a case where driving of the sub heaters iscontrolled so as to eliminate the temperature distribution bycalculating a temperature difference between a temperature detected froma temperature sensor arranged in the vicinity of the ejection openingused for the recording and a temperature detected from a temperaturesensor arranged in the vicinity of the ejection opening that is not usedfor the recording, the following problem may occur. In a case where ause frequency of the ejection opening used for the recording is high,the temperature of the temperature sensor in its vicinity is increased,and the temperature difference from the temperature sensor arranged inthe vicinity of the ejection opening that is not used for the recordingis expanded, so that the power of the sub heater in the vicinity of theejection opening that is not used for the recording is to be furtherincreased. As a result, the detection temperature difference and thetemperature distribution are to be eliminated, but the entire recordinghead accumulates heat, and the temperature is increased. Thus, it isfound that a state of an excessive increase in the temperature isestablished, and an ejection performance may be decreased.

SUMMARY OF THE INVENTION

The present invention has been made in view of the above-describedproblem and aims at performing recording while density unevennessderived from a temperature distribution in which a temperature on acentral side in an ejection opening array is higher than a temperatureon an end part side in the ejection opening array is suppressed.

In view of the above, according to an aspect of the present invention,there is provided an image recording apparatus that includes a recordinghead including at least a substrate, a recording element array in whicha plurality of recording elements that are arranged on the substrate ina predetermined direction and generate thermal energy for ejecting inkof a predetermined color, a first detection element that detects atemperature in a vicinity of the recording element at a first positionin the predetermined direction in the recording element array, a seconddetection element that detects a temperature in a vicinity of therecording element at a second position that is different from the firstposition in the predetermined direction in the recording element array,and a heating element that performs heating of ink in the vicinity ofthe plurality of recording elements arranged in the recording elementarray, and a control unit that controls heating by the heating elementon the basis of the temperatures detected by the first and seconddetection elements, in which the control unit controls the heating bythe heating element in a manner that the heating by the heating elementis executed in a case where a temperature difference between thetemperature detected by the first detection element and the temperaturedetected by the second detection element is higher than a firstthreshold.

Further features of the present invention will become apparent from thefollowing description of exemplary embodiments with reference to theattached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an image recording apparatus accordingto an exemplary embodiment.

FIG. 2 is a schematic view of a recording head according to theexemplary embodiment.

FIGS. 3A and 3B are perspectives of the recording head according to theexemplary embodiment.

FIG. 4 is a schematic view for describing a recording control systemaccording to the exemplary embodiment.

FIG. 5 is an explanatory diagram for describing a driving control of asub heater according to the exemplary embodiment.

FIGS. 6A and 6B are explanatory diagrams for describing a temperaturetransition according to the exemplary embodiment.

FIGS. 7A and 7B illustrate a temperature distribution according to theexemplary embodiment.

FIG. 8 is an explanatory diagram for describing the driving control ofthe sub heater according to the exemplary embodiment.

FIG. 9 is a table diagram illustrating a threshold in accordance with arecording condition according to the exemplary embodiment.

FIGS. 10A and 10B are explanatory diagrams for describing thetemperature transition according to the exemplary embodiment.

FIGS. 11A and 11B illustrate the temperature distribution according tothe exemplary embodiment.

FIGS. 12A, 12B, and 12C are table diagrams illustrating the thresholdsin accordance with the recording condition according to the exemplaryembodiment.

FIG. 13 is an explanatory diagram for describing the driving control ofthe sub heater according to the exemplary embodiment.

FIG. 14 is a table diagram illustrating the threshold in accordance withthe recording condition according to the exemplary embodiment.

FIGS. 15A and 15B are explanatory diagrams for describing thetemperature transition according to the exemplary embodiment.

FIG. 16 is an explanatory diagram for describing the driving control ofthe sub heater according to the exemplary embodiment.

FIG. 17 is a table diagram illustrating the threshold in accordance withthe recording condition according to the exemplary embodiment.

FIGS. 18A and 18B are explanatory diagrams for describing thetemperature transition according to the exemplary embodiment.

FIGS. 19A, 19B, and 19C are table diagrams illustrating the threshold inaccordance with the recording condition according to the exemplaryembodiment.

DESCRIPTION OF THE EMBODIMENTS

Hereinafter, a first exemplary embodiment of the present invention willbe described in detail with reference to the drawings.

First Exemplary Embodiment (1) Mechanical Configuration of an ImageRecording Apparatus (1-1) Outline of the Apparatus

FIG. 1 illustrates an external appearance of an image recordingapparatus (hereinafter, will be also referred to as printer) accordingto an exemplary embodiment of the present invention. This printer is aso-called serial scanning type printer and is configured to scan arecording head in a scanning direction (X direction) perpendicular to aconveyance direction (Y direction) of a recording medium P to record animage.

A configuration of this image recording apparatus and an outline of anoperation at the time of recording will be described by using FIG. 1.First, the recording medium P is conveyed in the Y direction by a sheetfeeding roller driven via a gear by a sheet feeding motor that is notillustrated in the drawing from a spool 6 that holds the recordingmedium P. Whereas, a carriage unit 2 is scanned along a guide shaft 8extending in the X direction at a predetermined conveyance position by acarriage motor that is not illustrated in the drawing. Subsequently, inthe process of this scanning, an ejection operation from the ejectionopenings is performed by a recording head (described below) which can bedetachably attached to the carriage unit 2 at a timing based on apositional signal obtained by an encoder 7, and a certain band widthcorresponding to a nozzle array range is recorded. According to thepresent exemplary embodiment, a configuration is adopted in which thescanning is performed at a scanning speed at 40 inches/second, and theejection operation is performed at a timing of 600 dpi. Thereafter, theconveyance of the recording medium is performed, and the recording forthe next band width is further performed according to the configuration.

In the above-described printer, the image may be recorded in a unit areaon the recording medium by performing the scanning once (so-calledone-pass recording), or the image may be recorded by performing thescanning plural times (so-called multi-pass recording). In a case wherethe one-pass recording is performed, the conveyance of the recordingmedium by an amount corresponding to the band width may be performedbetween the respective scanning operations. On the other hand, in a casewhere the multi-pass recording is performed, a configuration may beadopted that the conveyance is not performed for each scanning, andafter the scanning is performed plural times with respect to the unitarea on the recording medium, the conveyance by an approximate amountcorresponding to the one band is performed in this unit area. Inaddition, as the other multi-pass recording, a method has been proposedwith which sheet feeding by an approximate amount corresponding to the1/n band is performed after data thinned out by a predetermined maskpattern is recorded for each scanning, and the scanning is performedagain, so that the image is completed by performing the scanning and theconveyance plural times (n times) with respect to the unit area on therecording medium by varying nozzles involved in the recording.

A flexible printed circuit board (not illustrated) for supplying asignal pulse for ejection driving, a head temperature adjustment signal,and the like is attached to a recording head 9. The other end of theflexible printed circuit board is connected to a control circuit(described below) which includes a control circuit that executes acontrol of this printer.

It is noted that a carriage belt can be used for transmission of drivingforce to the carriage unit 2 from the carriage motor. However, insteadof the carriage belt, other driving methods can also be used. Forexample, a mechanism including a lead screw that is rotated and drivenby the carriage motor and extends in a main scanning direction and anengagement portion that is provided to the carriage unit 2 and engagedin a groove of the lead screw or the like can be used.

The fed recording medium P is nipped by a sheet feeding roller and apinch roller and conveyed to be guided to a recording position on aplaten 4 (main scanning area of the recording head 9). In general, sincea capping is applied to an orifice face of the recording head 9 in apause state, the capping is released before the recording is started toput the recording head 9 and the carriage unit 2 in a state in which thescanning can be performed. Thereafter, once data for one scanning isaccumulated in a buffer, the carriage unit 2 is scanned by a carriagemotor 3, and the recording is performed in the above-described manner.

(1-2) Configuration of the Recording Head

FIG. 2 is a schematic perspective view of the recording head 9 mountedto the carriage unit 2 of the above-described printer as viewed from adirection in which the ink is ejected. Herein, a plurality of ejectionopening arrays 11 to 16 that can eject ink of different color tones(including colors and densities) in the X direction including, forexample, ink of black (Bk), light cyan (Lc), cyan (C), light magenta(Lm), magenta (M), and yellow (Y) are arranged on two support substrates10 side-by-side on the recording head 9. Ink is supplied from inkintroduction portions 23 via ink passages inside the recording head 9 tothe respective ejection opening arrays. The ink is introduced from inktanks via supply tubes 45 to the ink introduction portions 23.

FIGS. 3A and 3B are perspectives for describing a detailed configurationof the support substrate 10 formed, for example, of a semiconductor. Itis noted that FIG. 3A is the perspective of the support substrate 10 asviewed from a direction perpendicular to an XY plane. FIG. 3B is theperspective of a position of a straight line IIIB-IIIB illustrated inFIG. 3A in a case where the support substrate 10 is viewed from adownstream side in the Y direction.

FIGS. 3A and 3B correspond to the ejection opening arrays 11 to 13 amongthe two support substrates 10 arranged side-by-side on the recordinghead 9. It is noted that, for simplicity, FIGS. 3A and 3B illustratecomponents having scale sizes different from actual scale sizes. Theejection opening arrays 11 to 13 according to the present exemplaryembodiment are respectively formed of two arrays each. The ejectionopening arrays 11 to 13 and electrothermal transducing element arrays(recording element arrays) are formed in the following manner. 640 eachper array, and 1280 in total of ejection openings 55 and electrothermaltransducing elements (also referred to as recording elements or mainheaters) 56 facing the ejection openings 55 are arranged in the Ydirection (predetermined direction) while these two arrays are shiftedfrom each other by 1200 dots/inch (dpi) with respect to the facing arrayin the Y direction (predetermined direction). It is noted that 1200 dpiis equivalent to approximately 0.02 mm according to the presentexemplary embodiment. While this electrothermal transducing element isapplied with a pulse, it is possible to generate thermal energy forejecting the ink from the ejection opening. The case where theelectrothermal transducing elements are used has been described herein,but it is also possible to use piezoelectric elements and the like. Anend part temperature sensor (detection element) 53 constituted by adiode that detects a temperature of the end part of the supportsubstrate 10 is formed on the support substrate 10 and in the end partin the Y direction in the ejection opening array. The end parttemperature sensor 53 is formed in a position in-between two ejectionopening arrays (for example, the ejection opening arrays 11 and 12) withrespect to the X direction and away from the ejection opening in the endpart by 0.2 mm with respect to the Y direction, and a configuration isadopted in which the one end part temperature sensor 53 detects the endpart temperature in the two ejection opening arrays. A central parttemperature sensor (detection element) 54 constituted by a diode thatdetects a temperature of the central part in the ejection opening arrayis formed in the central part in the Y direction in the ejection openingarray, and a configuration is adopted in which the one central parttemperature sensor 54 detects a central part temperature in the twoejection opening arrays. A sub heater (heating element) 17 that adjustsa temperature of the ink in the ejection opening is formed as onecontinuous member surrounding the three ejection opening arrays 11 to 13is located on an outer side of a nozzle array 15 by 1.2 mm with respectto the X direction and an outer side of a temperature sensor 20 by 0.2mm with respect to the Y direction. It is noted that, as schematicallyillustrated in FIG. 3B, the sub heater 17 and the central parttemperature sensor 54 are formed so as to be engaged with the supportsubstrate 10 inside an ejection opening member 57 provided on thesupport substrate 10. The electrothermal transducing element 56 isformed so as to be engaged with the support substrate 10 in the inkpassage.

(2) Configuration Example of a Control System

FIG. 4 illustrates a configuration example of a control circuit of theimage recording apparatus used according to the present exemplaryembodiment. In FIG. 4, a programmable peripheral interface (hereinafter,referred to as PPI) 101 receives an instruction signal (command) and arecording information signal including recording data which aretransmitted from a host computer 100 and transfers these signals to amicro processing unit (MPU) 102, and also transmits status informationof the printer to the host computer 100 when needed. The PPI 101 alsoperforms input and output with a console 106 including a setting inputunit with which a user performs various settings to the printer, adisplay unit that displays a message to the user, and the like, andreceives signal inputs from a sensor group 107 including a home positionsensor that detects that the carriage unit 2 and the recording head 9are at a home position, a capping sensor, and the like.

The MPU 102 controls respective units in the printer in accordance witha control program stored in a control ROM 105. A RAM 103 stores receivedsignals or is used as a work area of the MPU 102 and temporarily storesvarious pieces of data. A font generation ROM 104 stores patterninformation such as characters and recording while corresponding to codeinformation and outputs various pattern information while correspondingto the input code information. A print buffer 121 stores recording datarasterized onto the RAM 103 or the like and has a capacity correspondingto recording of a plurality of rows. The control ROM 105 can store notonly the above-described control program but also fixed datacorresponding to program data used in the process of a control describedbelow (for example, data for the MPU to determine a starting timing of asub heater control related to the main parts according to the presentexemplary embodiment) or the like. These respective units are controlledby the MPU 102 via an address bus 117 and a data bus 118. The MPU 102also obtains the temperatures detected from the end part temperaturesensor 53 and the central part temperature sensor 54 which are arrangedin the recording head 9 and generates the above-described program dataon the basis of these temperatures.

Motor drivers 114, 115, and 116 respectively drive a capping motor 113,the carriage motor 3, and a sheet feeding motor 5 in accordance with thecontrol of the MPU 102.

A sheet sensor 109 detects the presence or absence of the recordingmedium, that is, whether or not the recording medium is supplied to aposition where the recording by the recording head 9 can be performed. Adriver 111 drives a heat generation unit (main heater, sub heater) ofthe recording head 9 in accordance with the above-described programdata. A temperature and humidity sensor 122 detects an environmenttemperature and an environment humidity in an installment environment ofthe printer main body. A power supply unit 124 supplies power to theabove-described respective units and includes an AC adopter and abuttery as a driving power supply apparatus.

In a recording system constituted by the above-described printer and thehost computer 100 that supplies the recording information signal to theprinter, when the recording data is transmitted by the host computer 100via a parallel port, an infrared port, a network, or the like, requiredcommands are added to its leading part. The commands include, forexample, a type of the recording medium on which the recording isperformed (a type such as plain paper, OHP sheet, or glossy paper, andfurthermore, a type of a special recording medium such as transfer film,heavy paper, or banner paper), a medium size (A0, A1, A2, B0, B1, B2, orthe like), a recording quality (draft, high quality, medium quality,emphasis on a particular color, a type of monochrome/color, or thelike), a sheet feeding path (ASF, manual sheet feeding, sheet feedingcassette 1, sheet feeding cassette 2, or the like set in accordance witha mode and a type of feeding unit of the recording medium of theprinter, for example), the presence or absence of automateddiscrimination for an object, and the like. In a case where aconfiguration in which application of treatment liquid for improving afixing property of the ink on the recording medium is performed isadopted, information for setting the presence or absence of theapplication or the like may be transmitted as a command in some cases.

Pieces of data used for the recording are read on the printer side fromthe control ROM 105 described above in accordance with these commands,and the recording is performed on the basis of those pieces of data. Thedata includes, for example, data for determining the number of recordingpasses when the above-described multi-pass recording is performed, theink ejection amount per the recording medium unit area, the recordingdirection, and the like. In addition to the above, the data includes amask type for the data thinning applied when the multi-pass recording isperformed, a driving condition of the recording head 9 (for example, ashape of a driving pulse applied to the heat generation unit, anapplication time, or the like), a size of a dot, a condition for therecording medium conveyance, the number of colors to be used, andfurthermore, a carriage speed, and the like.

Hereinafter, an example of the driving control of the sub heateraccording to the present exemplary embodiment will be described indetail.

FIG. 5 is a flow chart for describing a flow of a control for changing athreshold of the sub heater according the present exemplary embodimentin accordance with the number of times to perform the scanning withrespect to the unit area.

When the recording of the image is started (step S101), first, the mainscanning of the recording head on the recording medium is started (stepS102). Subsequently, a difference (temperature difference) ΔT (° C.)between the temperature detection value from the end part temperaturesensor 53 and the temperature detection value from the central parttemperature sensor 54 is calculated to start comparison with apreviously set threshold Tth (° C.) (step S103). According to thepresent exemplary embodiment, the threshold Tth (° C.) is set as 3° C.The threshold Tth (° C.) can be appropriately set as a different value.An appropriate value for eliminating the temperature different iscalculated by a simulation or the like, and information related to thevalue can be previously stored in the control ROM 105 in the recordingapparatus.

When it is determined that the temperature difference ΔT (° C.) ishigher than the threshold Tth, to reduce the temperature differencebetween the end part side and the central side, driving of the subheater is started (step S104). On the other hand, the temperaturedifference ΔT (° C.) when it is determined that the temperaturedifference ΔT (° C.) is lower than or equal to the threshold Tth, thesub heater is not driven (step S105). In a case where the driving of thesub heater is already executed at that time, the driving of the subheater is stopped.

Thereafter, it is determined whether or not the image recording is ended(step S106), and when the recording of all the data is ended, the imagerecording operation is ended (step S107). In a case where the recordingof all the data is not ended, the flow returns to step S102, and thesimilar processing is continued until the data is ended.

FIGS. 6A and 6B illustrate the temperature transition of the end parttemperature sensor value and the central part temperature sensor valueduring the recording depending on the presence or absence of the controlbased on the flow described in FIG. 5.

FIG. 6A illustrates the temperature transition of the ejection openingarray 12 in a case where an image of an A0 size light cyan 100% duty isrecorded without applying the present exemplary embodiment to theconfiguration. Herein, the head temperature is increased to 35° C.before the recording is started by the temperature adjustment controlusing the sub heater and the electrothermal transducing element used forejecting the ink before the recording is started, and then the recordingis started. To perform 100% duty recording, the ink is ejected from therespective ejection openings in the ejection opening array 12 at asubstantially uniform frequency. However, the area on the end part sidein the Y direction tends to dissipate the heat via the support substrate10 to open air, and it tends to be more difficult for the temperature toincrease as compared with the central part. Therefore, in 108 secondslater when the recording is ended, the end part temperature sensor valuebecomes approximately 42° C., and the central part temperature sensorvalue becomes approximately 50° C.

On the other hand, FIG. 6B illustrates the temperature transition of theejection opening array 12 in a case where the similar recording isexecuted while the present exemplary embodiment is applied to theconfiguration. After an elapse of 34 seconds since the recording isstarted, the temperature difference between the end part temperaturesensor value and the central part temperature sensor value exceeds 3°C., and the heating by the sub heater 17 is started. Since the subheater centrally heats the end part side in the Y direction where theheat dissipation is likely occur, the increase speed of the end parttemperature sensor value is accelerated. For that reason, thetemperature difference between the central part temperature sensor valueand the end part temperature sensor value is diminished, and thetemperature difference at the time of the recording end is approximately1° C. It is however noted that the temperature of the entire recordinghead is slightly increased because of the heating by the sub heater, andthe recording is ended while the end part temperature sensor value isapproximately 51° C., and the central part temperature sensor value isapproximately 52° C.

FIGS. 7A and 7B illustrate the temperature distribution of the ejectionopening array 12 at the time of the recording end. FIG. 7A illustratesthe temperature distribution in a case where the present exemplaryembodiment is not applied to the configuration, and FIG. 7B illustratesthe temperature distribution in a case where the present exemplaryembodiment is applied to the configuration.

In a case where the present exemplary embodiment is not applied to theconfiguration, as illustrated in FIG. 7A, the temperature distributionin which the temperature in the central part in the ejection openingarray is high and the temperature in the end part is low is obtained. Incontrast to this, by applying the present exemplary embodiment to theconfiguration, as illustrated in FIG. 7B, the temperature distributionin the ejection opening array becomes substantially uniform.

In this manner, according to the present exemplary embodiment, the subheater is driven in a case where the temperature difference is higherthan the threshold, and the driving of the sub heater is stopped in acase where the temperature difference is lower than or equal to thethreshold. Thus, the temperature distribution in the ejection openingarray (in the recording element array) is set to be substantiallyuniform, and the density unevenness derived from the temperaturedistribution can be appropriately suppressed.

Second Exemplary Embodiment

According to the present exemplary embodiment, a different threshold isset in accordance with the number of times to perform the scanning withrespect to the unit area on the recording medium by the recording head.

It is noted that descriptions on parts similar to the above-describedfirst exemplary embodiment will be omitted.

When the recording is performed by the multi-pass recording method withwhich the scanning is performed plural times with respect to the unitarea on the recording medium to perform the recording, even in a casewhere the temperature difference in the ejection opening array is thesame, if the number of times to perform the scanning with respect to theunit area is relatively high, the density unevenness is not soconspicuous. If the number of times to perform the scanning with respectto the unit area is relatively low, the density unevenness may notablyoccur in some cases. It is conceivable that this is because, if thenumber of times to perform the scanning is high even in a case where thefluctuation of the ejection amount occurs, the density unevenness can besuppressed to some extent by the effect of the multi-pass recordingmethod, but if the number of times to perform the scanning is low, theeffect of the multi-pass recording method is reduced, and the densityunevenness is not sufficiently suppressed.

Therefore, according to the present exemplary embodiment, a low value isset as the threshold in a case where the number of times to perform thescanning with respect to the unit area is relatively low to facilitatethe driving of the sub heater. On the other hand, in a case where thenumber of times to perform the scanning is relatively high, since thedensity unevenness is not so conspicuous even when the temperaturedifference occurs, a high value is set as the threshold to make itdifficult for the sub heater to be driven.

Hereinafter, an example of the driving control of the sub heateraccording to the present exemplary embodiment will be described indetail.

FIG. 8 is a flow chart for describing a flow of a control for changingthe threshold of the sub heater in accordance with the number of timesto perform the scanning with respect to the unit area according to thepresent exemplary embodiment.

First, in step S501, when the image recording is started, the MPU 102recognizes information related to the number of times to perform thescanning with respect to the unit area as the information related to therecording condition on the basis of the information from the RAM 103(step S502). According to the present exemplary embodiment, informationon a recording mode executed when the recording is performed among aplurality of recording modes that will be described below is obtained asthe information related to the number of times to perform the scanning.

The image recording apparatus according to the present exemplaryembodiment can execute three recording modes including a high speedrecording mode, a standard recording mode, and a high image qualityrecording mode. Herein, the high speed recording mode refers to arecording mode in which the scanning is performed twice with respect tothe unit area to perform the recording (two-pass recording) isperformed. The standard recording mode refers to a recording mode inwhich the scanning is performed four times with respect to the unit areato perform the recording (four-pass recording). The high image qualityrecording mode refers to a recording mode in which the scanning isperformed eight times with respect to the unit area to perform therecording (eight-pass recording).

Herein, in a case where the temperature distribution occurs to someextent in the ejection opening array, the density unevenness derivedfrom the temperature distribution may be more conspicuous in the imagerecorded in the standard recording mode than the image recorded in thehigh image quality recording mode at the same temperature difference.Furthermore, the density unevenness derived from the temperaturedistribution may be still more conspicuous in the image recorded in thehigh speed recording mode than the image recorded in the standardrecording mode. It is conceivable that this is because the multi-passeffect can suppress the density unevenness in a case where the number oftimes to perform the scanning with respect to the unit area is high evenat the temperature difference as the described above.

In view of the above-described point, according to the present exemplaryembodiment, as illustrated in FIG. 9, any one of values is selected fromamong a plurality of candidate values to be set as the threshold Tth ineach recording mode (step S503). For example, in the case of thetwo-pass recording equivalent to the high speed recording mode, 3° C. isselected as the threshold temperature difference Tth at which thedriving of the sub heater is started. In the case of the four-passrecording equivalent to the standard recording mode, 5° C. is selected,and in the case of the eight-pass recording or higher equivalent to thehigh image quality recording mode, 10° C. is selected. It is noted thatdifferent values can be appropriately set as the thresholds Tth (° C.)in the respective recording modes described above. Appropriate valuesfor eliminating the temperature difference in the respective recordingmodes can be calculated by simulations and the like, and informationrelated to those values can be previously stored in the control ROM 105in the recording apparatus.

When the main scanning is started in step S504, the difference(temperature difference) ΔT (° C.) between the temperature detectionvalue from the end part temperature sensor 53 and the temperaturedetection value from the central part temperature sensor 54 iscalculated, comparison with the threshold Tth (° C.) set in step S503 isstarted (step S505).

When it is determined that the temperature difference ΔT (° C.) ishigher than the threshold Tth, to reduce the temperature differencebetween the end part side and the central side, driving of the subheater is started (step S506). On the other hand, when it is determinedthat the temperature difference ΔT (° C.) is lower than or equal to thethreshold Tth, the sub heater is not driven (step S509). In a case wherethe driving of the sub heater is already executed at that time, thedriving of the sub heater is stopped.

Thereafter, it is determined whether or not the image recording is ended(step S507), and when the recording of all the data is ended, the imagerecording operation is ended (step S508). In a case where the recordingof all the data is not ended, the flow returns to step S102, and thesimilar processing is continued until the data is ended.

Hereinafter, while a case where the recording is performed in the highspeed recording mode and a case where the recording is performed in thestandard recording mode are taken as an example, the temperaturetransition when the present exemplary embodiment is applied to theconfiguration will be described. Herein, as an example, descriptionswill be given of a case where an image recorded similarly as in thefirst exemplary embodiment is the image of the A0 size light cyan 100%duty, the head temperature is increased to 35° C. before the recordingstart by the temperature adjustment control using the sub heater and theelectrothermal transducing element used for ejecting the ink before therecording start, and then the recording is started.

As may be understood from FIG. 9, in a case where the recording isperformed in the high speed recording mode according to the presentexemplary embodiment, the threshold Tth is set as 3° C. Therefore, thetemperature transition occurs as illustrated in FIG. 6B, and thesubstantially uniform temperature distribution can be obtained at thetime of the recording end as illustrated in FIG. 7B.

On the other hand, as may be understood from FIG. 9, in a case where therecording is performed in the standard recording mode, the threshold Tthis set as 5° C. Herein, FIGS. 10A and 10B illustrate the temperaturetransition in a case where the image recording similar to FIGS. 6A and6B is performed in the standard recording mode.

FIG. 10A illustrates the temperature transition in a case where thepresent exemplary embodiment is not applied to the configuration. In 192seconds later when the recording is ended, the end part temperaturesensor value becomes approximately 40° C., and the central parttemperature sensor value becomes approximately 47° C.

On the other hand, FIG. 10B illustrates the temperature transition in acase where the present exemplary embodiment is applied to theconfiguration. After an elapse of 102 seconds since the recording isstarted, the temperature difference between the end part temperaturesensor value and the central part temperature sensor value exceeds 5°C., and the heating by the sub heater 17 is started. For that reason,the temperature difference between the end part temperature sensor valueand the central part temperature sensor value is diminished, and thetemperature difference at the time of the recording end is approximately2° C. It is however noted that the temperature of the entire recordinghead is slightly increased because of the heating by the sub heater, andthe recording is ended while the end part temperature sensor value isapproximately 45.5° C., and the central part temperature sensor value isapproximately 47.5° C.

FIGS. 11A and 11B illustrate the temperature distribution of theejection opening array 12 at the time of the recording end. It is notedthat FIG. 11A illustrates the temperature distribution in a case wherethe present exemplary embodiment is not applied to the configuration,and FIG. 11B illustrates the temperature distribution in a case wherethe present exemplary embodiment is applied to the configuration.

In a case where the present exemplary embodiment is not applied to theconfiguration, as illustrated in FIG. 11A, the temperature distributionin which the temperature of the central part in the ejection openingarray is high and the temperature of the end part is low is obtained. Incontrast to this, by applying the present exemplary embodiment to theconfiguration, as illustrated in FIG. 11B, the temperature distributionof the ink in the ejection opening array becomes substantially uniformin the Y direction.

In this manner, according to the present exemplary embodiment, differentthresholds are set in accordance with the number of times to perform thescanning with respect to the unit area. The sub heater is driven in acase where the temperature difference is higher than the threshold, andthe driving of the sub heater is stopped in a case where the temperaturedifference is lower than or equal to the threshold. Thus, thetemperature distribution in the ejection opening array (in the recordingelement array) is set to be substantially uniform, and the densityunevenness derived from the temperature distribution can beappropriately suppressed. In the high speed recording mode, the numberof times to perform the scanning is low, and the density unevennessderived from the temperature distribution in the ejection opening arraymay be easily visibly recognized. However, according to the presentexemplary embodiment, the temperature difference between the centralpart temperature sensor value and the end part temperature sensor valuecan be reduced to approximately 1° C. Accordingly, it is possible toeffectively suppress the density unevenness derived from the temperaturedistribution in the ejection opening array. On the other hand, since themulti-pass effect may be more easily attained in the standard recordingmode than the high speed recording mode, the temperature distribution inthe ejection opening array is not easily visibly recognized as thedensity unevenness. For that reason, according to the present exemplaryembodiment, although the temperature difference between the central parttemperature sensor value and the end part temperature sensor valuebecomes approximately 2° C., it is possible to effectively suppress thedensity unevenness.

In addition, a result is obtained that the central part temperaturesensor value is increased by approximately 2° C. at the time of therecording end by the execution of the sub heater control in the highspeed recording mode as compared with a case where the sub heatercontrol is not executed. If the above-described control is continued,the entire recording head accumulates the heat, and the temperature isincreased. Therefore, instability of the ejection accompanied by theexcess temperature increase may be caused in some cases. In view of theabove, in the standard recording mode according to the present exemplaryembodiment, it is possible to minimize the period during which the subheater control is executed by setting the threshold at which the subheater control is started to be higher than that in the high speedrecording mode. Therefore, it is possible to suppress the temperatureincrease to approximately 0.5° C. in the standard recording mode.

Third Exemplary Embodiment

According to the second exemplary embodiment, the descriptions have beengiven of the mode in which the threshold for driving the sub heater isdetermined in accordance with the number of times to perform thescanning with respect to the unit area as the recording condition.

In contrast to this, according to the present exemplary embodiment,descriptions will be given of a mode in which the threshold for drivingthe sub heater is determined in accordance with a recording conditionother than the number of times to perform the scanning.

It is noted that descriptions on parts similar to the above-describedfirst and second exemplary embodiments will be omitted.

As described above, even when the temperature distribution in theejection opening array is the same, a degree of the density unevennessderived from the temperature distribution may differ in accordance withthe type of the recording medium, the recording duty, or the humidity inthe vicinity of the surface of the recording medium when the recordingis performed. It is noted that the recording duty according to thepresent exemplary embodiment refers to a ratio of the number of pixelareas where the ink is actually ejected to the number of pixel areaswhere the ink can be ejected with respect to the unit area on therecording medium. The pixel area is an area in the unit area equivalentto a pixel and refers to an area where the ink of the same can besupplied by only a single droplet at a maximum. For example, an image ofthe 100% recording duty is a so-called solid image formed while the inkis ejected to all the pixel areas in the unit area. An image of the 0%recording duty is an image where the ink is not ejected to any of thepixel areas in the unit area. In this manner, it may be understood thatthe recording duty is in proportion to the ejection amount of the inkejected with respect to the unit area.

For example, since the ink easily bleeds on the plain paper among theplain paper, the coated paper, and the glossy paper, it is difficult tovisibly recognize the density unevenness derived from the temperaturedistribution even if the density unevenness is generated. On the otherhand, since it is difficult for the ink to be bled on the glossy paper,the visibility of the density unevenness derived from the temperaturedistribution is high.

In a case where the image to be recorded correspond to a middle grayscale (for example, the recording duty is 30 to 50%), the fluctuation ofthe coverage on the recording medium of the ink droplet at the time ofthe recording position misalignment is large as compared with the caseof a low gray scale (for example, the recording duty is 0 to 30%) or thecase of a high gray scale (for example, the recording duty is 50 to100%). For that reason, the density unevenness derived from thetemperature distribution is more easily visibly recognized in the middlegray scale than the high gray scale or the low gray scale.

Furthermore, a rate of moisture absorption of the recording medium in acase where the humidity is low is different from that in a case wherethe humidity detected by a humidity sensor (humidity detection unit) ishigh, and it becomes more difficult for the ink to be bled. For thatreason, in a case where the density unevenness derived from thetemperature distribution occurs, the density unevenness is easilyvisibly recognized.

In view of the above-described point, according to the present exemplaryembodiment, information related to any one of the type of the recordingmedium, the recording duty, and the humidity in the vicinity of thesurface of the recording medium is obtained as the information relatedto the recording condition in step S502 of FIG. 8. Subsequently, anappropriate threshold is selected in accordance with the recordingcondition in step S503 of FIG. 8 to perform the driving control of thesub heater.

FIGS. 12A, 12B, and 12C are table diagrams illustrating the thresholdsfor driving the sub heater. It is noted that FIGS. 12A, 12B, and 12Crespectively illustrate the appropriate thresholds in accordance withthe type of the recording medium, the recording duty, and the humidity.

For example, a setting is made in a manner that the threshold isrelatively high in a case where the type of the recording medium is theplain paper where the density unevenness is less likely to beconspicuous, and the threshold is relatively low in a case where theglossy paper where the density unevenness is more likely to beconspicuous. When the image of the middle gray scale where the densityunevenness is more likely to be conspicuous is recorded, the thresholdis set to be relatively low as compared with the case where the image ofthe high gray scale or the low gray scale is recorded. Since the densityunevenness is more likely to be conspicuous in a case where the humidityis low, the threshold is set to be relatively low as compared with thecase where the humidity is high.

According to the present exemplary embodiment, even in a case where thedensity unevenness derived from the temperature distribution is morelikely to be conspicuous depending on the type of the recording medium,the recording duty, or the humidity, it is possible to perform therecording while the density unevenness is appropriately suppressed.

Fourth Exemplary Embodiment

According to the present exemplary embodiment, a threshold temperaturedifference at which the sub heater control is driven is set inaccordance with a detected temperature of the temperature sensor.

It is noted that descriptions on parts similar to the above-describedfirst to third exemplary embodiments will be omitted.

FIG. 13 is a flow chart illustrating a flow of a control for setting athreshold at which the sub heater control is started in accordance withthe detected temperature of the temperature sensor in the central partduring the recording.

FIG. 14 is a table diagram illustrating an appropriate thresholdtemperature in accordance with the detected temperature of thetemperature sensor.

First, when the image recording is started in step S1101, a highestreaching temperature Tmax (° C.) at that time among detectedtemperatures of the temperature sensor in the central part is obtained(step S1102). In a case where Tmax is higher than or equal to 61° C.(step S1103), 0 is set as a sub heater control starting flag Hon (stepS1105). In a case where Tmax is lower than 61° C., 1 is set as the subheater control starting flag Hon (step S1104), and also the thresholdTth at which the sub heater control is started in accordance with Tmaxis set on the basis of the table illustrated in FIG. 14 (step S1106).

At the same time when the main scanning is started (step S1107), a stateof the sub heater control starting flag is checked, and also comparisonof the difference ΔT (° C.) between the temperature detection value fromthe end part temperature sensor 53 and the temperature detection valuefrom the central part temperature sensor 54 with the threshold Tth (°C.) set in step S1106 is started (step S1108) When it is detected thatthe sub heater control starting flag Hon is 1, and also the differenceΔT of the temperature detection values (° C.) becomes higher than thethreshold Tth (° C.) set from the highest reaching temperature of thecentral part temperature sensor, the control of the sub heater isstarted such that the temperature difference between the end parttemperature sensor and the central part temperature sensor is decreased(step S1109). On the other hand, in a case where the temperaturedifference ΔT is lower than or equal to the threshold Tth, the drivingof the sub heater is stopped (step S1112).

Thereafter, it is determined whether or not the image recording is ended(step S1110), and when the recording of all the data is ended, the imagerecording operation is ended (step S1111).

According to the above-described control, under the conditions where thetemperature of the ejection opening array is low, and a concern that thetemperature difference between the central part and the end part may beabruptly expanded in a case where the recording of the high duty imageis performed exists, the sub heater control is started early, and theoccurrence of the density unevenness can be avoided. On the other hand,in a case where the temperature of the ejection opening array is high,and the support substrates also involve the heat accumulation, aprobability that the temperature difference is abruptly expanded issmall even when the recording of the high duty image is performed. Forthat reason, the sub heater control does not need to be started inadvance, and the start of the sub heater control is delayed until thetemperature difference to such an extent that the density unevennessdoes not occur is reached, and it is possible to avoid the excesstemperature increase of the recording head. In addition, in a case wherethe temperature of the ejection opening array is about to reach thetemperature area where the excess temperature increase may occur (61° C.or higher according to the present exemplary embodiment), the driving ofthe sub heater is not performed, and it is possible to prioritize theejection performance of the recording head.

FIGS. 15A and 15B illustrate the temperature transition for performingthe scanning twice after the recording start when the recording in thehigh speed recording mode similar to the first exemplary embodiment isexecuted in a case where the central part temperature sensor value is41° C. and a case where this value is 51° C.

FIG. 15A illustrates the transition of the central part temperaturesensor value and the end part temperature sensor value in a case wherethe recording is started from a state in which the central parttemperature sensor value is 41° C. Immediately after the recording isstarted, the temperature difference between the temperature sensorsexceeds 2° C., and at the time when the first scanning is ended, the endpart temperature sensor value is increased to 47° C., and the centralpart temperature sensor value is increased to 52° C. Therefore, thetemperature difference exceeds 4° C. at which the density unevenness isvisibly recognized in the high speed recording mode. In view of theabove, if the sub heater control is stated when the temperaturedifference reaches 2° C. according to the present exemplary embodiment,it is possible to suppress the temperature difference expansion duringthe recording. The temperature difference can be set as approximately 3°C. according to the present exemplary embodiment.

On the other hand, FIG. 15B illustrates the temperature transition in acase where the recording is started from a state in which the centralpart temperature sensor is 51° C. Since the recording head itselfaccumulates the heat at the time of the recording start, the temperatureincrease transition by the recording is moderate, and the temperaturedifference between the temperature sensors stays at approximately 2.5°C. even at the time of the recording end. Therefore, the sub heatercontrol does not necessarily need to be started immediately after thetemperature difference reaches 2° C. as in the case where the recordingstart temperature is 41° C. According to the present exemplaryembodiment, since 3.5° C. that is short of approximately 4° C. at whichthe density unevenness may occur is set as the threshold at which thecontrol of the sub heater is started, the sub heater is not driven inthe two-scanning recording, and it is possible to avoid the furtherexcess temperature increase of the recording head.

As described above, the temperature distribution in the ejection openingarray is eliminated by carrying out the exemplary embodiment of thepresent invention, and the density unevenness can be avoided. Inaddition to the above, it is also possible to suppress the decrease inthe ejection performance while the excess temperature increase of therecording head is avoided.

It is noted that the configuration has been adopted in which thethreshold temperature difference at which the sub heater control isstarted is set in accordance with the temperature of the central parttemperature sensor value according to the present exemplary embodiment,but the value of the end part temperature sensor may be used, or acompletely different temperature sensor may also be used. As long as thetemperature in the vicinity of the ejection opening array can bedetected as the recording condition, any sensor value may be used.

In addition, the configuration has been adopted in which the sub heatercontrol is not executed in a case where a risk of the excess temperatureincrease exists in the recording head according to the present exemplaryembodiment, but the similar effects can be attained when a configurationin which the input energy to the sub heater is reduced by decreasing thedriving duty of the sub heater, reducing the driving time, or the like.

Fifth Exemplary Embodiment

According to the present exemplary embodiment, the threshold temperaturedifference at which the sub heater is driven and the thresholdtemperature difference at which the driving of the sub heater is endedare set to have different thresholds.

It is noted that descriptions on parts similar to the above-describedfirst to fourth embodiments will be omitted.

FIG. 16 is a flow chart for describing a flow of a control in which thethreshold temperature difference at which the sub heater control isstarted and the threshold temperature difference at which the sub heatercontrol is ended are set to have different thresholds.

First, when the image recording is started in step S1401, the MPU 102obtains the information related to the number of times to perform thescanning with respect to the unit area on the basis of the informationfrom the control ROM 105 (step S1402). Next, as illustrated in FIG. 17,a reference is made to a setting table of a threshold temperaturedifference Tthon at which the sub heater control is started and athreshold temperature difference (predetermined value) Tthoff at whichthe sub heater control is stopped in each of the recording modescorresponding to the number of times to perform the scanning, and thethreshold temperature difference is set in the relevant recording mode(step S1403). Herein, the threshold temperature difference Tthoff atwhich the sub heater control is stopped is set to be lower than thethreshold temperature difference Tthon at which the sub heater controlis started in each of the recording modes.

At the same time when the main scanning is started (step S1404),comparison of the difference ΔT (° C.) between the temperature detectionvalue from the end part temperature sensor 53 and the temperaturedetection value from the central part temperature sensor 54 with thethreshold Tthon (° C.) set in step S1403 is started (step S1405). Whenit is detected that the difference ΔT of the temperature detectionvalues (° C.) is higher than the threshold Tthon (° C.) set from therecording mode, the sub heater is configured to be driven so as toreduce the temperature difference between the end part temperaturesensor and the central part temperature sensor (step S1406). Next, it isdetermined whether or not the difference ΔT (° C.) of the temperaturedetection values is lower than or equal to the threshold Tthoff set instep S1403 (is lower than or equal to a predetermined value) (stepS1407), and when it is detected that the difference is lower than orequal to Tthoff, the sub heater is stopped (step S1408).

Thereafter, it is determined whether or not the image recording is ended(step S1409), and when the recording of all the data is ended, the imagerecording operation is ended (step S1410).

According to the above-described control, as compared with the casewhere the sub heater drive temperature is the same as the sub heaterstop temperature, the heating time by the sub heater can be sufficientlysecured, and it is facilitated to attain the effect of setting thetemperature difference between the central part and the end part in theejection opening array to be uniform. For example, FIG. 18A illustratesthe temperature transition when the drive temperature and the stoptemperature of the sub heater are set be the same (3° C. in this case)in a case where the recording of the A0 size light cyan 100% duty imagesimilar to that in the first exemplary embodiment is executed in thehigh speed recording mode. The difference between the central parttemperature sensor value and the end part temperature sensor valuebecomes 3° C. in 34 seconds after the recording start, and the drivingof the sub heater is started. However, the end part temperature sensorvalue is momentarily increased by the heating effect by the sub heater.As a result, the temperature difference becomes below 3° C., andimmediately after that, the sub heater is stopped. Subsequently, the subheater repeats the control ON and OFF, and the recording is ended whilethe temperature difference between the end part temperature sensor valueand the central part temperature sensor value is hardly reduced andremains approximately 3° C.

On the other hand, FIG. 18B illustrates the temperature transition in acase where the threshold Tthoff (° C.) at which the sub heater controlis stopped is set to be lower than the threshold Tthon (° C.) at whichthe sub heater control is started as illustrated in FIG. 17. Thetemperature difference becomes 3° C. in 34 seconds after the recordingstart and exceeds Tthon (° C.), and the sub heater control is started.After that, the end part temperature sensor value is increased by theheating effect by the sub heater, and the temperature difference withthe central part temperature sensor value becomes below 3° C. but is notbelow Tthoff (° C.), so that the sub heater control is continued. In 56seconds after the recording start, the temperature difference is below1° C., and the sub heater control is stopped. Since the sub heatercontrol is stopped, the increase in the end part temperature sensorvalue is stagnated, and the temperature difference with the central parttemperature sensor value is expanded. However, the recording is endedwhile the temperature difference is within 3° C., and the sub heatercontrol is not resumed. The temperature difference at the time of therecording end is becomes approximately 1.5° C., and the temperaturedifference is diminished as compared with the case where the starttemperature and the stop temperature of the sub heater control have thesame setting.

In this manner, by setting the threshold temperature difference Tthoffat which the sub heater control is stopped to be lower than thethreshold temperature difference Tthon at which the sub heater controlis started, the heating time does not run short by the frequent ON/OFFcontrol of the sub heater, and the sub heater control is sufficientlycontinued, so that it becomes facilitated to reduce the temperaturedifference between the central part and the end part in the ejectionopening array. In addition, as illustrated in FIGS. 15A and 15B, thedifference between the threshold Tthon (° C.) at which the sub heatercontrol is started and the threshold Tthoff (° C.) at which the subheater control is stopped can be changed in accordance with the numberof times to perform the scanning with respect to the unit area.Accordingly, the excess temperature increase of the recording head isavoided in such a manner, for example, that the sub heater control canbe continued for a sufficiently long time in a case where the risk ofthe occurrence of the density unevenness is high, and the sub heatercontrol is kept to a minimum in a case where the risk of the occurrenceof the density unevenness is low, and an optimal control can be carriedout.

As described above, according to the present exemplary embodiment, notonly the temperature distribution in the ejection opening array is setto be uniform, and the density unevenness can be suppressed, but alsothe decrease in the ejection performance by the excess temperatureincrease of the recording head can be suppressed.

It is noted that the configuration has been adopted in which the starttemperature and the stop temperature of the sub heater are set inaccordance with the number of times to perform the scanning with respectto the unit area according to the present exemplary embodiment, but theother mode can also be executed. For example, a configuration may beadopted in which the start temperature and the stop temperature of thesub heater is set in accordance with the type of the recording medium,the recording duty, the humidity in the vicinity of the surface of therecording medium, or the temperature of the ink in the ejection openingarray. The start temperature and the stop temperature of the sub heatercontrol may be set to be different from each other also according to amode in which previously set thresholds are used similarly as in thefirst exemplary embodiment.

Other Embodiments

Embodiments of the present invention can also be realized by a computerof a system or apparatus that reads out and executes computer executableinstructions recorded on a storage medium (e.g., non-transitorycomputer-readable storage medium) to perform the functions of one ormore of the above-described embodiment(s) of the present invention, andby a method performed by the computer of the system or apparatus by, forexample, reading out and executing the computer executable instructionsfrom the storage medium to perform the functions of one or more of theabove-described embodiment(s). The computer may comprise one or more ofa central processing unit (CPU), micro processing unit (MPU), or othercircuitry, and may include a network of separate computers or separatecomputer processors. The computer executable instructions may beprovided to the computer, for example, from a network or the storagemedium. The storage medium may include, for example, one or more of ahard disk, a random-access memory (RAM), a read only memory (ROM), astorage of distributed computing systems, an optical disk (such as acompact disc (CD), digital versatile disc (DVD), or Blu-ray Disc (BD)™),a flash memory device, a memory card, and the like.

According to the respective exemplary embodiments described above, therecording head having the mode in which the sub heater is arranged so asto surround the ejection opening arrays 11 to 13 is used, but the othermode can also be executed. The similar effect can be attained accordingto a mode in which the temperature difference between the end parttemperature and the central part temperature in the ejection openingarray is reduced by arranging a plurality of sub heaters in the vicinityof the ejection openings, for example.

In addition, according to the respective exemplary embodiments describedabove, the mode has been described in which the driving of the subheater is regularly controlled in accordance with the temperaturedifference, but the other mode can also be executed. For example, tosuppress the decrease in the ejection amount or the non-ejection thatoccurs when the temperature is notably low as in the related art, themode be combined with a mode in which the sub heater is driven in a casewhere the detected temperature is lower than or equal to thepredetermined threshold and the driving of the sub heater is stopped ina case where the detected temperature is higher than the predeterminedthreshold. In this case, for example, a mode may be adopted in which (i)the sub heater is driven in a case where the detected temperature islower than or equal to 40° C., (ii) the driving of the sub heater isstopped in a case where the detected temperature is higher than 40° C.,and also the temperature difference is lower than or equal to 3° C., and(iii) the sub heater is driven again to eliminate the temperaturedifference in a case where the detected temperature is higher than 40°C., and also the temperature difference is higher than 3° C. It is notedthat, as the temperature of this case, any one of the end parttemperature sensor and the central part temperature sensor may be usedas a representative temperature, or an average value of the two valuesmay also be used as the representative temperature.

Furthermore, according to the respective exemplary embodiments describedabove, the mode has been described in which the image is recorded byperforming the scanning on the recording medium plural times, but theother mode can also be executed. For example, the respective exemplaryembodiments can also be applied to a mode in which a long recording headhaving a length longer than the width direction of the recording mediumis used, and the ink is ejected from the recording head to recording thetime while the recording medium is conveyed once in a directionintersecting with the width direction.

Moreover, the controls according to the respective exemplary embodimentsdescribed above can also be executed in combination. For example, thedriving of the sub heater may be controlled in accordance with both thenumber of times to perform the scanning with respect to the unit areaand the value of the central part temperature sensor as the recordingcondition. In this case, in the driving control of the sub heaterillustrated in FIG. 13, in a case where the sub heater control startingflag Hon is 1, in step S1106, the threshold Tth may be determined whilefollowing the table in which the threshold for driving the sub heater isset in accordance with the number of times to perform the scanning withrespect to the unit area and the value of the central part temperaturesensor respectively illustrated in FIGS. 19A, 19B, and 19C.

The image recording apparatus and the image recording method accordingto the respective exemplary embodiments have been described, but theinvention may include an image processing apparatus and an imageprocessing method with which data for performing the image recordingmethod described in the respective exemplary embodiments is generated.Furthermore, the present invention can be widely applied to a mode inwhich a program that causes the image recording apparatus to function isprepared in a separate form from the image recording apparatus, a modein which the program is provided to a part of the image recordingapparatus, and the like.

With the image recording apparatus, the image recording method, and thenon-transitory computer-readable storage medium according to theexemplary embodiment of the present invention, it is possible to performthe recording while the density unevenness derived from the temperaturedistribution is suppressed in a manner that the temperature in thecentral part side in the ejection opening array is set to be higher thanthe temperature in the end part side.

While the present invention has been described with reference toexemplary embodiments, it is to be understood that the invention is notlimited to the disclosed exemplary embodiments. The scope of thefollowing claims is to be accorded the broadest interpretation so as toencompass all such modifications and equivalent structures andfunctions.

This application claims the benefit of Japanese Patent Application No.2014-109047, filed May 27, 2014, which is hereby incorporated byreference herein in its entirety.

What is claimed is:
 1. An image recording apparatus comprising: arecording head including at least a substrate, a recording element arrayin which a plurality of recording elements that are arranged on thesubstrate in a predetermined direction and generate thermal energy forejecting ink of a predetermined color, a first detection element thatdetects a temperature in a vicinity of the recording element at a firstposition in the predetermined direction in the recording element array,a second detection element that detects a temperature in a vicinity ofthe recording element at a second position that is different from thefirst position in the predetermined direction in the recording elementarray, and a heating element that performs heating of ink in thevicinity of the recording elements at the first position and the secondposition among the plurality of the recording elements arranged in therecording element array; and a control unit that controls the heating bythe heating element on the basis of the temperatures detected by thefirst and second detection elements, wherein the control unit controlsthe heating by the heating element in a manner that the heating by theheating element is executed in a case where a temperature differencebetween the temperature detected by the first detection element and thetemperature detected by the second detection element is higher than afirst threshold.
 2. The image recording apparatus according to claim 1,wherein the control unit controls the heating by the heating element ina manner that the heating by the heating element is stopped in a casewhere the temperature difference is lower than or equal to a secondthreshold.
 3. The image recording apparatus according to claim 2,wherein the first position is one end part in the predetermineddirection in the recording element array, and the second position is acentral part in the predetermined direction in the recording elementarray.
 4. The image recording apparatus according to claim 2, whereinthe heating element is arranged at least in the vicinity of the one endpart in the predetermined direction in the recording element array inthe recording head.
 5. The image recording apparatus according to claim2, further comprising: an obtaining unit that obtains informationrelated to a recording condition when an image is recorded; and adetermination unit that determines the first threshold on the basis ofthe recording condition indicated by the information obtained by theobtaining unit.
 6. The image recording apparatus according to claim 5,further comprising: a scanning unit that can scan the recording headwith respect to a unit area on the recording medium plural times,wherein the obtaining unit obtains information related to a number oftimes to perform the scanning with respect to the unit area of therecording head by the scanning unit as the information related to therecording condition, and wherein the control unit (i) determines a firstvalue as the first threshold in a case where the number indicated by theinformation obtained by the obtaining unit is a first number of timesand (ii) determines a second value that is lower than the first value asthe first threshold in a case where the number indicated by theinformation obtained by the obtaining unit is a second number of timeswhich is lower than the first number of times.
 7. The image recordingapparatus according to claim 5, wherein the obtaining unit obtainsinformation related to an ejection amount of the ink ejected withrespect to the unit area on the recording medium as the informationrelated to the recording condition, and wherein the control unit (i)determines a third value as the first threshold in a case where theejection amount indicated by the information obtained by the obtainingunit is a first amount and (ii) determines a fourth value that is lowerthan the third value as the first threshold in a case where the ejectionamount indicated by the information obtained by the obtaining unit is asecond amount that is lower than the first amount.
 8. The imagerecording apparatus according to claim 7, wherein the control unitdetermines a fifth value that is higher than the fourth value as thefirst threshold in a case where the ejection amount indicated by theinformation obtained by the obtaining unit is a third amount that islower than the second amount.
 9. The image recording apparatus accordingto claim 5, wherein the obtaining unit obtains information related to atype of the recording medium as the information related to the recordingcondition, and wherein the control unit (i) determines a sixth value asthe first threshold in a case where the type of the recording mediumindicated by the information obtained by the obtaining unit is plainpaper and (ii) determines a seventh value that is lower than the sixthvalue as the first threshold in a case where the type of the recordingmedium indicated by the information obtained by the obtaining unit iscoated paper.
 10. The image recording apparatus according to claim 9,wherein the control unit determines an eighth value that is lower thanthe seventh value as the first threshold in a case where the type of therecording medium indicated by the information obtained by the obtainingunit is glossy paper.
 11. The image recording apparatus according toclaim 5, wherein the obtaining unit obtains information related to atype of the recording medium as the information related to the recordingcondition, and wherein the control unit (i) determines a ninth value asthe first threshold in a case where the type of the recording mediumindicated by the information obtained by the obtaining unit is plainpaper and (ii) determines a tenth value that is lower than the ninthvalue as the first threshold in a case where the type of the recordingmedium indicated by the information obtained by the obtaining unit isglossy paper.
 12. The image recording apparatus according to claim 5,further comprising: a humidity detection unit that detects a humidity ina vicinity of a surface of the recording medium when the ink is ejectedonto the recording medium, wherein the obtaining unit obtainsinformation related to the humidity detected by the humidity detectionunit as the information related to the recording condition, and whereinthe control unit (i) determines an eleventh value as the first thresholdin a case where the humidity indicated by the information obtained bythe humidity detection unit is a first humidity and (ii) determines atwelfth value that is lower than the eleventh value as the firstthreshold in a case where the humidity indicated by the informationobtained by the humidity detection unit is a second humidity that islower than the first humidity.
 13. The image recording apparatusaccording to claim 5, wherein the obtaining unit obtains informationrelated to any one of the temperatures including the temperaturedetected by the first detection element and the temperature detected bythe second detection element as the information related to the recordingcondition, and wherein the control unit (i) determines a thirteenthvalue as the first threshold in a case where the temperature indicatedby the information obtained by the obtaining unit is a first temperatureand (ii) determines a fourteenth value that is lower than the thirteenthvalue as the first threshold in a case where the temperature indicatedby the information obtained by the obtaining unit is a secondtemperature that is lower than the first temperature.
 14. The imagerecording apparatus according to claim 5, wherein the determination unitdetermines the first threshold from among a plurality of candidatevalues in accordance with the recording condition indicated by theinformation obtained by the obtaining unit.
 15. The image recordingapparatus according to claim 2, wherein the second threshold is a samevalue as the first threshold.
 16. The image recording apparatusaccording to claim 2, wherein the second threshold is a value lower thanthe first threshold.
 17. The image recording apparatus according toclaim 2, further comprising: a second obtaining unit that obtains arepresentative temperature on the basis of the temperatures detected bythe first and second detection elements, wherein the control unitcontrols the heating by the heating element in a manner that (i) theheating by the heating element is executed in a case where therepresentative temperature obtained by the second obtaining unit islower than or equal to a third threshold, (ii) the heating by theheating element is executed in a case where the representativetemperature obtained by the second obtaining unit is higher than thethird threshold, and also the temperature difference is higher than thefirst threshold, and (iii) the heating by the heating element is stoppedin a case where the representative temperature obtained by the secondobtaining unit is higher than the third threshold, and also thetemperature difference is lower than or equal to the second threshold.18. The image recording apparatus according to claim 2, wherein therecording element array has the plurality of recording elements arrangedin a range longer than a width in the predetermined direction of therecording medium.
 19. An image recording method comprising: using arecording head including at least a substrate, a recording element arrayin which a plurality of recording elements that are arranged on thesubstrate in a predetermined direction and generate thermal energy forejecting ink of a predetermined color, a first detection element thatdetects a temperature in a vicinity of the recording element at a firstposition in the predetermined direction in the recording element array,a second detection element that detects a temperature in a vicinity ofthe recording element at a second position that is different from thefirst position in the predetermined direction in the recording elementarray, and a heating element that performs heating of ink in thevicinity of the plurality of recording elements arranged in therecording element array; and controlling the heating by the heatingelement on the basis of the temperatures detected by the first andsecond detection elements to record an image, wherein the heating by theheating element is controlled in a manner that the heating by theheating element is executed in a case where a temperature differencebetween the temperature detected by the first detection element and thetemperature detected by the second detection element is higher than afirst threshold, and also the heating by the heating element is stoppedin a case where the temperature difference is lower than or equal to asecond threshold.
 20. A non-transitory computer-readable storage mediumstoring a program that causes a computer to execute the image recordingmethod according to claim 19.